Lock-up damper disk of a torque converter

ABSTRACT

A damper disk for a lock-up clutch disposed in a torque converter includes a clutch plate as an input member, damper springs for elastically connecting the clutch plate to a turbine of a torque converter and a drive plate. The drive plate is made of sheet metal and is fixed to the clutch plate. The drive plate includes rims and support walls for holding the damper springs, as well as, radially outer projections and inner projected walls engaging the springs. Claws rigidly connected to the turbine are disposed between the projections and projected walls. The rims includes stoppers at the ends thereof which are radially inwardly inclined for preventing axial movement of the damper springs.

FIELD OF THE INVENTION

The present invention relates to a lock-up damper disk for use as alock-up clutch disk of a torque converter and is operable to damp torquevibration transmitted from an engine.

BACKGROUND OF THE INVENTION

FIGS. 14 and 15 illustrate the lock-up clutch damper disc disclosed inthe U.S. Pat. No. 4,240,532, and FIG. 16 and 17 illustrate an embodimentdisclosed in the Japanese patent publication No. 61-28126.

In FIG. 14, a damper disk 100, used as a lock-up clutch disc is disposedbetween a main part 101 of a torque converter and a front cover 102welded at a portion 104 to a pump 103 and is connected at an outerperipheral coupling 106 to an input shaft 114. A turbine 107 isconnected by rivets 110 to a hub 109 splined onto an output shaft 115. Astator 108 has a one-way clutch 111, of which inner race 112 is splinedto a stationary cylindrical shaft 116. The damper disk 110 comprises aclutch plate 117, or piston, axially slidably supported on the hub 109,a drive ring 118 welded to a rear surface of the clutch plate 117,circumferentially extending damper springs 120 disposed in pockets 119in the drive plate 118, and a driven plate 122 which have claws 121engaging with the damper springs 120 and fixed to the turbine 107. Afriction facing 123 is fixed to a front surface of the clutch plate 117.

When the facing 123 on the clutch plate 117 is pressed onto the frontcover 102 by a difference between pressures at the opposite sides of theclutch plate 117, the front cover 102 is connected to the turbine 107through the damper disk 100.

As shown in FIG. 15, the drive plate 118 has outer rims 125 and innersupport walls 126, for forming the spring pockets 119 therebetween, aswell as projections 127 and 128 which form spring receivers or springsupports at opposite sides of the spring pockets 119. Each spring pocket119 accommodates a set of one long damper spring 120 and one shortdamper spring 120a. The claws 121 are disposed between adjacent springs120 and 120a.

There are following disadvantages in the structures disclosed in theU.S. Pat. No. 4,240,532.

In the assembling operation, each pair of the springs 120 and 120 mustbe held apart in each pocket 119 so as to insert the claw 121therebetween. This operation is laborious and it is difficult to checkthe correct relationship between the springs and claws during theassembling.

In a high speed driving, a strong centrifugal force is applied from thesprings to the outer rims 25. However, when the clutch is engaging ordisengaging, i.e., when the clutch plate axially moves, the springs 120and 120a directly engaging the claws 121 tend to axially move togetherwith the claws 121 with respect to the drive plate 118. Therefore, alarge friction is caused between the springs 120 and 120a and the outerrims 125, which prevents the smooth movement of the clutch plate, andthus, the smooth operation of the clutch.

Since the centrifugal force of the springs 120 and 120a is directlyapplied to the outer rims 125, the outer rims 125 must be made of athick plate. As shown in FIG. 14, because the drive plate 118 has athickness nearly the same as that of the clutch plate 117, the springpockets are axially narrow so that it may be impossible to disposedamper springs having a large diameter therein, even when the largesprings are desirable for achieving effective damping function. Further,the thick plate causes increase in the weight, which deteriorates theresponse of the clutch. The thick plate also causes increase in cost.

In order to avoid the above disadvantages, such structures may beemployed, as shown in FIG. 14a, in which end portions of the drive plate118 fixed to the clutch plate 117 are radially inwardly curved to formstoppers 125a for preventing axial movement of the damper springs 120.These inclined stoppers 125a increase the strength of the rims 125 sothat the thickness of the plate can be reduced to some extent. However,because the the centrifugal force of the damper springs 120 is supportedonly by the drive plate 118, it is impossible to sufficiently reduce thethickness of the plate.

In the device shown in FIGS. 16, and 17, the clutch plate 117 isintegrally provided with outer rims 117a which directly support thedamper springs 120. Spring supports 130 which support the ends of thedamper springs 120 is riveted to the clutch plate 117. The springsupports 130 include support walls 131. Spring seats 132 (FIG. 17) isassociated to the springs.

There is however following disadvantages in the device shown in FIGS. 16and 17.

Because it is necessary to use a thick plate for the clutch plate 117for preventing deformation of the outer rims 117a to which thecentrifugal force of the damper springs 120 are applied, the materialcost thereof is high.

Since the damper springs are radially and axially supported by thecylindrical surfaces of the rims 117a and the radial surface of theclutch plate 117, respectively, it is necessary to increase the hardnessof the surfaces for preventing the wear thereof. However, heat treatmentfor the hardening causes deformation of the clutch plate 117, so that itis necessary to polish it for maintaining a high flatness of the facing123, resulting in a high manufacturing cost.

Since a plurality of spring supports 130 are used, the assembling islaborious and the precision in sizes may deteriorate.

Accordingly, it is an object of the invention to provide a damper diskovercoming the above-noted disadvantages.

SUMMARY OF THE INVENTION

The invention provides a damper disk for a lock-up clutch of a torqueconverter wherein the damper disk is disposed between a front coverconnected to a pump of the torque converter and a turbine of the torqueconverter connected to an output shaft, and includes an axially movableclutch plate for frictional engagement with the front cover and aplurality of circumferentially extending damper springs for elasticallyconnecting said clutch plate to said turbine; characterized in that adrive plate made of sheet metal is fixed at the radially inner portionsthereof to clutch plate, drive plate includes rims and support walls forholding radially outer and inner sides of the damper springs,respectively, as well as, radially outer projections and inner projectedwalls located between the circumferentially adjacent damper springs forengaging the ends thereof, claws rigidly connected to turbine aredisposed between radially adjacent projections and projected walls,respectively, the rims include stoppers at the ends thereof which areradially inwardly inclined for preventing axial movement of the dampersprings, and spring seats are fitted into the ends of the dampersprings, respectively.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an elevation of a damper disk of an embodiment of theinvention view with a half of a driven plate removed;

FIG. 2 is a sectional view taken along the II-II in FIG. 1;

FIG. 3 is a sectional view taken along the line III--III in FIG. 1;

FIG. 4 is a fragmentary schematic view illustrating a part of a damperdisk;

FIG. 5 is a fragmentary perspective view of the same;

FIG. 6 is an elevation of the drive plate alone;

FIG. 7 is a sectional view taken along the line VII--VII in FIG. 6;

FIG. 8 is a sectional view taken along the line VIII--VIII in FIG. 6;

FIG. 9 is a fragmentary elevation of a driven plate;

FIG. 10 is a sectional view of the driven plate;

FIG. 11 is an exploded perspective view illustrating a damper spring andspring seats;

FIG. 12 is a sectional view of a torque converter incorporating the diskaccording to the invention;

FIG. 12A is a sectional view of a torque converter incorporating thedisk of another embodiment of the invention;

FIG. 13 is a graph illustrating damping characteristics;

FIGS. 14 and 14A are fragmentary sectional views illustrating a priorart;

FIG. 15 is a fragmentary sectional view taken along the line XV--XV inFIG. 14;

FIGS. 16 is a fragmentary sectional view illustrating another prior art;and

FIG. 17 is a fragmentary sectional view of the structure in FIG. 16.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIGS. 1-5, a lock-up damper disk according to the inventioncomprises a drive ring or drive plate 13 made of sheet metal which isfixed by rivets 12 to a piston plate or clutch plate 11, a driven ringor driven plate 14 fixed by rivets (not shown) to a hub 109 (FIG. 12) ofthe turbine 107, and two kinds of damper springs 15 and 16 disposedbetween plates 13 and 14. The driven plate 14 may be welded to theturbine shell of the turbine 107, as shown in FIG. 12A.

The drive plate 13 includes outer peripheral rims 13a which extend alonginner surfaces of rims 11a at the outer peripheral of the clutch plate11. The rims 13a have the height, in the axial direction of the disk,slightly larger than that of the rims 11a of the clutch plate 11. Thedrive plate 13 also includes a plurality of circumferentially spacedsupport walls 17 radially inside the rims 13a. Each support wall 17 isintegrally formed by a portion of the drive plate 13 which is partiallycut and radially bent, so that an opening 18 (FIG. 5) having a shapecorresponding to the support wall 17 is formed radially outside thesupport wall 17. Each of the damper springs 15 and 16 which extend inthe circumferential direction are disposed in spring pockets 19 formedbetween the outer rims 13a and the support walls 17, and are preventedfrom dropping or disengaging in the radially outward and inwarddirections. The leading end of each outer rim 13a is radially inwardlybent to form a stopper 13b (FIG. 3).

As clearly shown in an enlarged view, FIG. 3b associated to FIG. 3, eachstopper 13b is fitted into the outer rim 11a of the clutch plate 11 witha slight space therebetween. Each stopper 13b is inclined radiallyinwardly at an angle of γ, and has a base end portion having an axiallength of α which is overlapped with the leading end portion of theouter rim 11a. Since the partially tapered stopper 13b continues to thepartially cylindrical outer rim 13a, the rims 13a have a high strength.The stoppers 13b extend nearly and partially around the damper springs16 and 15. Thus, the stoppers 13b receive the centrifugal force from thedamper springs 16 and 15 when they are deflected radially outwardly bythe centrifugal force, and deflect to contact the inner surface of theclutch plate rims 11a.

Each rim 11a in FIG. 3 protrudes a distance of α beyond a boundary Pbetween the outer rim 13a and the stopper 13b of the driven plate 13.This distance α between the leading end of the rim 11a and the boundaryP is preferably not less than 0.

The distance β of said space is in a predetermined range (e.g., 0.5mm),in which the elastic deformation of the rim 13a and the stoppers 13b isallowed without generating cracks thereat. In other words, the drive rim13 may be destroyed by cracks generated between the rims 13a and springreceivers 21A or 21B which are formed by cut and bent portions of theplate, as will be detailed, when the rims 13a elastically deform to alarge extent. However, in the illustrated structures, since thedeformation of the rims 13a is restricted by the rims 11a, the crackingand of the rims 13a is prevented.

The drive plate 13 also includes circumferentially spaced projectedwalls 20, which are located between the spring pockets 19, respectively,and a plurality of pairs of the projections 21A and 21B, which are alsolocated radially outside the walls 20 and between the spring pockets 19.The projected walls 20 are formed by portions of the plate 13 which arepartially cut and radially outwardly bent through about 90 degrees, sothat corresponding openings 22 are formed radially inside the projectedwalls 20, respectively. Each pair of the projections 21A and 21B areformed by a common portion of the plate 13 between the outer rims 13a,which is partially cut and radially outwardly bent. A recess is formedbetween the projections 21A and 21B at each pair.

The driven plate 14 is integrally provided at the outer periphery withcircumferentially equally spaced claws or projections 23 projectingtoward the drive plate 13. Each claw 23 is located between the projectedwall 20 and the projections 21A and 21B of the drive plate 13.

The springs 15 and 16 consists of coil springs. The longer springs 15are circumferentially adjacent two by two, and each shorter spring 16 isdisposed between the spring pairs, each of which includes the twosprings 15. Spring seats 24 are fitted into opposite ends of each of thesprings 15 and 16. Each spring seat 24 has a leg 24a having a length ofL1 and fitted into each end of the spring. Each end surface 15a (FIG.11) of the spring is polished so that it may closely contact the springseat 24.

The members and parts described above are assembled as follows.

When the springs 15 and 16 equipped with the spring seats 24 are fittedin the spring pockets 19 in the drive plate 13, the springs 15 and 16are slightly compressed, as shown in FIG. 1, and the spring seats 24contact the projected walls 20 and the projections 21A or 21B,respectively. The driven plate 14 is then assembled to the drive plate13. In this assembled condition, the spring seats 24 for the longsprings 15 contact the claws 23 of the driven plate 14 without a space.However, each spring seat 24 at one end of each short spring 16 islocated apart from the claw 23 with a circumferential space da, FIG. 1,therebetween, and each spring seat 24 at the other end of the spring 16is located apart from the claw 23 with a space db therebetween. Thespaces da in the positive rotation direction indicated at an arrow A inFIG. 1 is longer than the spaces db in the reverse direction.

As shown in FIG. 4, the projected wall 20 are circumferentiallyretracted or short with respect to the projections 21A and 21B so thatthe damper springs may form nearly linear shapes rather than a shapecurved in the circumferential direction of the disk, when the disk stopsor rotates at a low speed. Whereby, at the high speed driving, thedamper springs 15 are curved radially outwardly, so that each springseat 24 moves away from the projected wall 20 to form a space L, FIG. 4,between the seat 24 and the drive plate claw 23. Thus the clutch plate11 and the drive plate 13 can axially smoothly move with respect to theclaw 23, resulting in smooth engagement and disengagement operation ofthe clutch.

As shown in FIGS. 2 and 3, a facing 25 is fixed to the outer peripheralportion of the clutch plate 11. As shown in FIG. 6, apertures 26 formedin the drive plate 13 for said rivets 12 (FIG. 2) are formed at convexportions which are circumferentially spaced at the inner peripheralportion of the drive plate. As shown in FIG. 9, apertures 27 for therivets which fix the driven plate 14 to the turbine is formed at theinner peripheral portions of the driven plate 14. As shown in FIGS. 1and 9, the driven plate 14 is provided with equally spaced circularopenings 28 for reducing the weight thereof.

When the lock-up clutch engages to transmit a torque in a positivedirection indicated by the arrow A, the torque is initially transmittedfrom the projected walls 20 and the projections 21A of the drive plate13 to the claws 23 of the driven plate 14 through the long springs 15and the spring seats 24. After the long springs 15 are compressed forthe amount corresponding to the space da in FIG. 1, the projected walls20 and the projections 21A of the drive plate 13 engage with the springseats 24 at the ends of the short springs 16, so that the short springs16 start to be compressed, and thus, the torque is also transmittedthrough the short springs 16. Thus, relationship between the torsionangle and the transmitted torque changes and inclination of dampercharacteristics increases at an angle αa (or αb), as shown in FIG. 13.

When the negative torque is transmitted, the operation is performedsimilarly to that described above, except for that the projections 21Bfunction to compress the springs instead of the projections 21A.

In the assembling operation, the damper springs 15 and 16 equipped withthe spring seats 24 are fitted in the spring pockets 19 and engage withthe projected walls 20 and the projections 21A or 21B, so that they areprevented from radially dropping by the rims 13a and the support walls17 of the drive plate 13. Therefore, it is not necessary to manuallykeep the damper springs 15 and 16 during the assembling of the driveplate 13 and the drive plate 14.

According to the invention, as described hereinbefore, there arefollowing advantages.

Since the cylindrical rims 13a at the outer periphery of the drive plate13 have the radially inwardly tapered ends (i.e., the stoppers), therims 13a have high strength against centrifugal force, so that thethickness of the plate 13 can be reduced. Because the damper springs areheld only by the drive plate 13, it is unnecessary to apply surfacehardening treatment to the clutch plate 11 and manufacturing cost can bereduced.

The springs seats 24 prevent the nonuniform contact and deviated loadbetween the springs and the plates 13 or 14 is durability can beincreased.

The spaces may be formed between the claws 23 and the damper springswhen the springs are radially outwardly curved by the centrifugalforces, in which case the clutch plate 17 can move smoothly axially.

The spring seats 24 may be formed to slidably contact the rims 13a, inwhich case the friction between the seats and rims generates ahysteresis torque and achieves high damping effect during low speeddriving where there is a large fluctuation of torque.

Because the damper springs 15 and the spring seats 24 are fitted intothe drive plate 13, they do not drop and are held in predeterminedpositions during the assembling, so that assembling can be easilyperformed.

As apparent from the above description, the lock-up damper diskaccording to the invention is usefully employed in the torque convertersof the automobiles and others.

What is claimed is:
 1. A damper disc for a lock-up clutch for a torqueconverter having a damper disc disposed between a front cover connectedto a pump of the torque converter and a turbine of the torque converterconnected to an output shaft and including an axially movable clutchplate for frictionally engaging said front cover and a plurality ofcircumferentially extending damper springs for elastically connectingsaid clutch plate to said turbine; characterized in that a drive platemade of sheet metal is fixed at radially inner portions thereof to saidclutch plate, said clutch plate, at its outer periphery, having anaxially extending clutch plate rim extending axially toward saidturbine, said drive plate including rims and support walls for holdingradially outer and inner sides of said damper springs, respectively, aswell as, radially outer projections and inner projected walls locatedbetween adjacent of said circumferentially extending damper springs forengaging ends of said adjacent damper springs, claws rigidly connectedto said turbine disposed between said radially adjacent projections andsaid projected walls, respectively, said drive plate rims extendingaxially toward said turbine radially inside said clutch plate rim andspaced radially inwardly from said clutch plate rim for forming aclearance therebetween, said drive plate rims including radiallyinwardly inclined stoppers at the ends thereof and projecting axiallybeyond the end of said clutch plate rim for preventing axial movement ofsaid damper springs, and spring seats fitted into ends of said dampersprings, respectively, said inner projected walls beingcircumferentially retracted with respect to said projections so thatsaid damper springs may form nearly linear shapes when said torqueconverter is at rest or turning at relatively low speed rather thanradially outwardly curved shapes formed by said damper springs at higherspeeds of said torque converter.
 2. A damper disc of claim 1 wherein theinner peripheral portion of said drive plate is riveted to said clutchplate.